Modern corn production tactics are being adopted that help to mitigate the impact of corn production on soil and water resources. Several of these tactics include no-tillage production, the use of delayed “sidedress” nitrogen fertilizer applications, delayed or postemergent herbicide applications and the establishment of cover crops during or following the corn crop. In no-tillage production, the field is not plowed or cultivated between crops. No-tillage production reduces the potential for soil erosion, conserves soil moisture, and reduces the energy associated with corn production. Sidedress nitrogen fertilizer applications reduce the potential for nitrogen fertilizer loss by applying the fertilizer immediately prior to the greatest demand by the crop. Postemergent herbicide applications allow corn producers to use less persistent herbicides prior to planting the crop and their use has been greatly increased by the development of both glyphosate and glufosinate herbicide resistant corn hybrids during the last decade. The establishment of cover crops following harvest has been promoted and is now required in some situations to minimize runoff and plant nutrient losses from either residual amounts of fertilizer not used by the corn crop or from animal manure applications made to the field following harvest.
The establishment of cover crops is often limited by the late fall harvest of the corn crop in some areas, which leaves little growing season for a cover crop, such as clover or ryegrass, to become established. Alternative seeding methods such as broadcasting the seed in the standing crop prior to harvest with a helicopter or ground based applicator have been inconsistent, especially in no-till fields that are covered with the residue from the previous crop. Researchers from Cornell (Scott et al., 1987) have reported successfully seeding cover crops during the late spring in fields that were tilled with minimal residue on the soil surface with no impact on crop yields. In this system, cover crop seeds were broadcast on the soil surface and incorporated using a row crop cultivator. A second study showed that this system could be used in soybean production as well (Hively and Cox, 2001).
Other researchers have proposed to plant a standing crop in an existing cover crop without the need to perform a cover crop seeding operation in the late spring. This tactic, often called a living mulch, can be effective but requires the suppression of the cover crop with a herbicide at the time of planting of the standing crop to avoid undue competition with the main, or standing, crop, such as corn. Canadian researchers have reported the effective use of seeding devices that can establish cover crops in a standing crop of corn in a tilled seedbed (see http://www.farmwest.com/index.cfm?method=library.showPage&librarypageid=66), however the device described only performs a seeding operation and is not adequate for use in no-till systems. Their experience demonstrated the potential utility of this in-season cover crop or “relay crop” as a part of corn production. Another unit for performing row crop cultivation and seeding has been developed for minimum tillage conditions, as shown in U.S. Pat. No. 5,333,559, but it lacks some of the elements and benefits of the present invention. A further device is shown in U.S. Pat. No. 5,370,068. Again, it lacks some elements and benefits of the present invention.
There remains a need for apparatus and methods for planting a cover crop between the rows of a standing crop in a no-till field.